Many electronic systems require cooling to dissipate heat generated by electronic components. Since radiation and conduction are less-effective heat transfer methods in an enclosed system, convective cooling solutions are often used. As such, a common electronic system may have one or more fans to drive air over components, exhaust warm air from the system and draw cooler air into the system.
Regardless of the implementation, a spinning cooling fan will emit some noise. Noise often results from the fan motor bearing, air moving past the fan blades and body of the fan, and the placement of the fan with respect to other objects (e.g., a vent in an electronic system chassis). Additionally, a more pronounced noise may result from multiple fans spinning at different speeds, where the noise profiles from the fans intersect to produce a “beating” sound. Given that the beating sound is often much louder and more annoying than the sound from an individual fan, conventional fan controllers attempt to spin proximately-located fans at precisely the same speed to reduce the beating sound.
Although the reduction of fan interference sounds is often important in a single electronic system with multiple fans, it becomes even more of an issue when multiple systems are placed in proximity to one another (e.g., in a computer server room). Since each system is likely to have at least one fan, the placement of multiple systems in the same room can dramatically increase the number of fans which may interfere with one another and create beating sounds. And moreover, given that the ambient air temperature of rooms containing multiple systems is often higher than rooms containing a single system, systems designed to be placed in the presence of other systems often contain more fans or larger fans that produce more noise. As such, the beating sounds are often louder, more prevalent and more annoying than those associated with a single system.
Despite attempts by conventional fan controllers to spin fans at the same speed, some fan speed differential and associated beating sound is likely to remain, especially in environments with multiple systems. Additionally, even if all fan speed differentials were eliminated, the ambient noise from the many fans is often very loud even without any beating. As such, it is often hard to identify audible faults. And even if a fault is identified, it is often hard to discern which system a given fault is associated with. Similarly, given the large number of solid and blinking lights on multiple systems placed near one another, visual faults (e.g., a blinking light) are also hard to identify and distinguish. Thus, given that most electronic systems are equipped with such audible and visual fault indicators, the price of the systems is increased while still providing poor fault indication.